Wound rotor synchronous machine current estimation using a linear Luenberger observer

Electrified transportation is a cornerstone of global decarbonization plans. However, high costs remain an obstacle. To address this, research has been undertaken to remove sensors and replace them with software. Simultaneously, with the volatility in pricing and supply of rare-earth magnets, alternatives to the permanent magnet synchronous machine are being sought. With fundamentally similar performance and the benefit of a controllable flux, the wound rotor synchronous machine is a promising alternative. This paper presents a linear Luenberger observer using the model incorporating rotor flux dynamics and nameplate parameters. It is shown that the wound rotor synchronous machine is observable with only one current sensor, either on the rotor or the stator. However, to overcome parameter error issues, a minimum of one current sensor on the rotor and one on the stator is deemed necessary to provide corrective integral feedback. Simulation results demonstrate that the designed observer can accurately estimate the rotor and stator currents in the presence of model error with the minimum sensor complement during transient and steady state operation.